Tuning High-Speed Adhesive Fracture Energies Using Silica-Modified Silicone Release Coatings

Poly(dimethylsiloxane) (PDMS) release coatings are crucial to pressure-sensitive adhesive (PSA) products because they protect PSAs from prematurely adhering to unintended surfaces or collecting debris. Before applying a PSA product onto a desired surface, PSA/release coating separation efficacy can be significantly improved by lowering the peel fracture energy required for high-speed separation (>100 m/min). Despite ubiquitous usage, developing a simple and low-cost solution to lower fracture energies has been challenging due to the lack of fundamental knowledge at high separation speeds. As PSA performance requirements are dictated by the final applications, lowering fracture energies by modifying release coatings is an attractive and practical strategy. In this work, hydrophobically functionalized fumed silica is incorporated into cross-linked PDMS release coatings differing in polymer network structure. Release coatings containing 1 wt % silica were found to have substantially lowered (up to 40%) fracture energies measured in a high-speed regime (100–300 m/min) than neat PDMS analogs, while the fracture energy remained unchanged in a low-speed regime (2.5–100 m/min). Silica addition in less densely cross-linked PDMS networks more profoundly lowered the fracture energy against an acrylic PSA, and factors including coating surface roughness, thickness variations, and material modulus upon the addition of silica were likely insignificant contributors. The rate of change of fracture energy with peel speed, analyzed using adhesion exponents, revealed potential changes in material deformation across the two regimes. Beyond exposing alternate approaches for lowering fracture energies in industrially relevant PDMS release coatings, this work highlights the need to understand mechanisms for tailoring properties of release coatings using silica.